The U.S.-led offensive against Iraq entered a new phase early Friday morning, with combat troops advancing into Iraq from northern Kuwait. As dawn broke Friday morning, U.S. and coalition troops were already moving north in Iraq's southern desert.

Allied forces rained artillery and rockets on Iraqi forces, as they broke through the first lines of defense near the Kuwaiti border. Armored vehicles from the U.S. First Marine Division were among the leading units, while tanks and troops from the U.S. Army's Seventh Cavalry also headed toward Baghdad in an armored column.

Coalition forces are also targeting key strategic points in southern Iraq. British troops conducted an assault on the strategic al-Faw peninsula, which is Iraq's access point to the Persian Gulf and the site of major oil facilities. There were also explosions heard in the northern city of Mosul.

Officers report encountering minimal opposition from the Iraqi military. Some Iraqi soldiers surrendered. Iraq's military says four of its soldiers have been killed and six others wounded.

Coalition forces suffered their first casualties in the war when a marine helicopter crashed in Kuwait, killing all 16 American and British personnel on board. The crash is believed to have been an accident, but an investigation is underway.

The ground assault follows a second night of targeted bombing in Baghdad. A wave of Tomahawk cruise missiles bombarded the city, this time targeting the main presidential palace, a ministry building and strongholds of the elite Republican Guard.

But U.S. officials say the nighttime strikes are not the beginning of what military planners have called a campaign of shock and awe they are prepared to unleash. That is the term for intensive bombing that had been expected early on.

Iraq has confirmed that it fired missiles at Kuwait Thursday, after earlier denying it. Kuwaiti officials said Thursday Iraq fired at least four Scud missiles at the Gulf state, two of which were intercepted by anti-missile rockets.

Reports also indicate several oilfields in southern Iraq might be on fire. Military planners are eager to secure the oil wells to prevent Iraqi forces from torching them, as they did to Kuwaiti oil fields during the 1991 Gulf war.

The fighting began Thursday morning, when U.S. forces launched missiles aimed at what was described as a senior leadership compound. Coalition officials say they are not yet sure of the results of that attack. Iraqi television announcers read a message said to be from Iraqi President Saddam Hussein, in which he said the invasion will fail.